The production of utility articles often sees a shaped article made from a metal, a plastic, rubber, foam, rigid foam or the like covered with a covering, made for example from a textile material, from leather, synthetic leather, polymeric film or the like. Particularly if such utility articles are exposed to mechanical stresses in the course of their use, a covering of this kind is to be fixed durably and reliably on the shaped article, so that in the course of service it does not slip, lose shape or even fall off again.
Such fixing has hitherto often been carried out using a liquid adhesive. This, however, entails problems such as unclean operations or unclean processing of the finished product by squeezing-out of adhesive, the migration of solvents from the adhesive into the covering or into the shaped article, or the evaporation of substances which are volatile—and frequently harmful to health—such as solvent residues from the adhesive over time. For very reliable adhesive bonds, reactive adhesives are popular among the liquid adhesives, but are hampered by the problem that they may require relatively long reaction times for curing.
In order to ensure very durable and reliable bonds, heat-activatedly bondable adhesives, especially in film form, have proven suitable. These adhesives are customarily non-tacky or of only weak tack at room temperature, but bond when a particular activation temperature is exceeded—especially by thermal melting and/or onset of a curing reaction—and ultimately set on cooling. Heat-activatedly bondable adhesives, however, generally require increased work during the bonding operation, since in addition to the heat that must be introduced externally, the influence of elevated pressure is also necessary in order to ensure an optimum bond. For this reason, bonding takes place customarily in hot presses, thus restricting this bonding method to planar, sheetlike substrates. Furthermore, compressible and heat-sensitive materials are not amenable to such an operation.